An electron in potentiometer experiences a force `2.4xx10^(-19)N`. The length of potentiometer wire is 6m. The emf of the battery connected across the wire is (electronic charge `=1.6xx10^(-19)C`)

Options

A. 6 V
B. 9 V
C. 12 V
D. 15 V

Answer

B

Explanation

Force experienced by electron F = q E
when E = Electric field intensity
`therefore 2.4 xx 10^(-19) = 1.6 xx 10^(-19) E implies E = 1.5` N/m
Moreover E = potential gradient
`E = (dV)/(dt)`
`therefore E xx t = V implies V= 1.5 xx 6 = 9 V`